DEC Technical Character Set summation symbol corners

[piotrunio-2...@wp.pl via Unicode]

In L2/98-354 ( www.unicode.org https://www.unicode.org/L2/L1998/98354.pdf ), 
the following characters were proposed for DEC Technical Character Set 
compatibility:   * E0AE  Right ceiling corner                   DEC Tech 03/05  
* E0AF  Right floor corner                     DEC Tech 03/06   However, in 
L2/00-159 ( www.unicode.org 
https://www.unicode.org/L2/L2000/00159-ucsterminal.txt ) which was incorporated 
into Unicode 3.2, those characters were withdrawn:     E0AE  Right ceiling 
corner                       U+2309 (1)
  E0AF  Right floor corner                         U+230B (1)
  (1) These characters were in Unicode all along, but the shape shown in the
    Unicode book was different from the shape on the terminal.  However,
    this is not sufficient reason to have two versions of the same symbol.   
However, in  urldefense.com DEC Technical Character Set (vt100.net)  the usage 
of those characters is explained as being parts of the summation symbol, and 
the left side of those characters connect to U+2500.   As far as I know, the 
floor and ceiling symbols usually have similar height to brackets (with the 
horizontal stroke being on bottom or top of the bracket height), and are used 
in pairs of left and right glyphs, which is completely different from the DEC 
Tech 03/05 and DEC Tech 03/06 characters. Is there any typographical precedent 
of floor and ceiling symbols being used with a centered horizontal stroke or 
with a horizontal connection to other characters?